According to the Washington Post, investigators have determined that as many as 20 U.S. Secret Service and military personnel were involved in the scandal. A preliminary investigation by the Defense Department, which included a review of video evidence, found that nine military personnel may have been involved, in addition to the 11 Secret Service agents who have had their security clearances revoked.

Meanwhile Cartagena Mayor Campo Elias Teran said local authorities were investigating whether some of the prostitutes involved in the scandal were minors, according to Colombian newspaper El Tiempo. “There is much speculation,” Teran commented, adding that rumors indicated that minors took part. Neither Teran nor Colombian police confirmed the allegations.

U.S. news agency CBS said the security personnel were sent home to the U.S. through Miami and questioned in Washington over their alleged hiring of prostitutes and other misconduct.

The men have been put on paid administrative leave and prohibited from entering Secret Service facilities worldwide.

“They are ‘do not admit’ and their equipment has been taken,” a law enforcement official told CBS News.

Two of the Secret Service agents allegedly involved in the misconduct are at the top of U.S. government’s pay scale. The two officials known as “GS-14s” are top of the General Schedule, the system in charge of civil service salaries. The two could earn as much as $110,000 per year.

U.S. news network ABC News has claimed the security officials revealed their identities by boasting at Cartagena brothel “Pley Club” that they worked for President Obama.

Members of the group, who reportedly included two Secret Servicemen and three members of the Counter-Assault Teams, allegedly said “we work for Obama” and “we’re here to protect him.”

A bouncer and a police source claimed the officials spent the night drinking expensive whisky and soliciting the services of the club’s prostitutes.

The men reportedly paid at least $200 for services from the “highest category” prostitutes at the club, and took more than 20 back to the hotel.

A dispute allegedly arose over the payment of a bill the following morning. Police were then called, with U.S. authorities directing police not to comment on that night or on the scandal, according to a senior officer in Cartagena.

The Pley Club is a well-known brothel in the historic city and tourist destination. Some taxi drivers in Cartagena are said to be paid a commission for recommending the club and its prostitutes to tourists.

The U.S. military’s top official has admitted that claims that U.S. Secret Service agents and military personnel hired prostitutes in Colombia are an embarrassment.

Joint Chiefs-of-Staff Chairman General Martin Dempsey said in a Pentagon news conference, “We let the boss down because nobody is talking about what went on in Colombia other than this incident (…) We are embarrassed.”

General Dempsey regretted that the incident diverted attention “from what was a very important regional commitment to our president [Barack Obama].”

The U.S. president said he expected a “rigorous” investigation, adding “If it turns out that some of these allegations that have been made in the press are confirmed, then of course I’ll be very angry.”

Secret Service deputy director Paul Morrissey said none of those involved belonged to the presidential protection division.